Compare Overpaying Student Loan Versus Other Debt

Student loan balances look terrifying and the instinct is to throw spare money at the biggest scary number, but UK student loans do not behave like normal debt and overpaying one is very often the wrong move. This explains why, then tells you where your spare cash is actually better spent instead.

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You have a UK student loan and other debt (credit card, personal loan) and {SPARE_AMOUNT} spare to put towards one of them. Student loan plan type: [plan 1, 2, 4, or 5]. Other debt interest rate: [rate].
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<task>
**Compare**:
1. How student loan interest and repayment actually works (income-linked, written off eventually) versus a normal debt
2. Whether overpaying the student loan is ever mathematically sensible for your plan type and likely earnings trajectory
3. Where the spare amount is better directed instead
4. The one scenario where overpaying a student loan would make sense
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<output_format>
- Explanation of why student loans behave differently to normal debt
- Clear recommendation for the spare amount
- The one exception scenario named
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